1. Field of the Invention
The present invention relates to distributed control systems and, in particular, concerns a control system for managing data communications in a distributed environment for a proton beam therapy device.
2. Description of the Related Art
Radiation particle therapy devices are commonly used to treat localized forms of cancer as well as other afflictions. These devices are used to target specific regions of a patient, e.g. a tumor, and direct a precisely aligned stream of atomic particles or electromagnetic radiation towards the target region. The energy from the stream results in localized cell damage and effectively disrupts the growth and progression of the tumor.
One particularly useful form of radiation therapy is proton beam therapy wherein protons form the energy stream used to irradiate the target regions of the patient. Like other types of beam directed radiation therapy, proton beam therapy requires the patient to be accurately positioned with respect to the beam source so that the proton stream irradiates only the desired target region. Otherwise, the stream could damage other healthy cells within the patient's body.
As described in detail in U.S. Pat. No. 4,905,267 a support apparatus is used to position the patient with a particular orientation and the support apparatus is further positioned on a treatment platform within a gantry structure of the proton treatment facility. The proton treatment facility may further comprise more than one such treatment apparatus for the purposes of accommodating multiple patients. Control and monitoring of the apparatus and components of the treatment facility are directed by computer and hardware subsystems which coordinate the activities of each treatment station. In addition to the mechanical apparatus used to position the patient, proton beam therapy requires numerous other systems and software components which are used to control beam intensity, modify beam position, perform digital imaging, monitor safety conditions, and other functions. Together these systems form a complex and distributed collection of hardware and software components. Additionally, in a proton treatment facility with more than one treatment apparatus, the complexity of the system is further increased by the additional requirements for system redundancy and selective control of each treatment apparatus.
The complex architecture of distributed systems such as radiation therapy devices present numerous obstacles in allowing for coordinated control by a single application and further create networking difficulties between the components of the system. One particular limitation of conventional distributed systems relates to the management of data communications between the various components of the distributed system which becomes more difficult as the size of the distributed system increases. This problem is particularly apparent when a radiation therapy device is designed to contain more than one treatment apparatus. As a result, providing a centralized control and monitoring solution becomes a cumbersome task due in part to the number of communications channels which must be maintained. Additionally, the complex communications mapping schema presents difficulties in insuring that all devices can communicate with one another. Oftentimes, modifying or upgrading a single component of the distributed system necessarily results in the need to modify the configuration for a large number of other components to which the modified component was connected. Improper modification of the configuration for these components can result in numerous problems including loss of system control, inaccurate system monitoring, and device failure.
In a radiation therapy device, significant reconfiguration of the existing mapping schema in the aforementioned manner is undesirable as it introduces potential control issues which must be resolved in order to insure patient safety. If these issues are not properly resolved or if there is unexpected loss of control of one of more of the components during operation of the radiation therapy device, patient injury may occur. Therefore it is desirable to increase the level of transparency between components within the radiation therapy device to make the system more tolerant to modification and component upgrades.
FIG. 1 illustrates a conventional distributed system 40 comprising a plurality of hardware devices 50 each of which perform selected operations and tasks. Control and maintenance of the hardware devices 50 is coordinated using one or more host applications or processes 60 which communicate with the hardware devices 50 through a plurality of communication channels or data paths 70. For each hardware device 50 that the host application or process 60 communicates, a separate communications channel 70 is typically established.
A number of difficulties arise when using this approach which limit the coordination and management capabilities of complex distributed systems such as radiation therapy devices. In particular, when a large number of hardware devices 50 are to be managed or monitored by the host applications or processes 60, the required number of communication channels 70 that must be established and maintained becomes increasingly large. In many instances this results in increased system overhead necessary to manage the communication channels 70 which may grow to a point where the maximum number of communication channels 70 supported by the operating system or hardware components is exceeded. Thus, conventional distributed systems 40 provide limited scalability due to restrictions in the number of communications channels 70 which can be accommodated. Additionally, as the complexity of the distributed system 40 increases it becomes more difficult to perform effective network monitoring and authentication as well as maintain secure firewall policies to insure adequate system security.
A further problem arises in complex distributed systems 40 to insure that individuals who work with the architecture of the existing system 40 understand the communications mapping of the channels 70 and services within the system 40. This is especially important for developers who must have specific knowledge of how the hardware devices 50 are interconnected in order to add new hardware components or functionality. Conventional approaches insufficiently address this problem and rely on esoteric mapping schemes which may be difficult to understand and develop around.
Conventional distributed environments are typically based on a client/server paradigm. The client/server approach uses one or more monolithic host applications to poll individual systems of the distributed environment and piece the information together as needed. This method of information distribution and coordination is undesirable for a number of reasons, including the above-described maintenance difficulties, lack of scalability, and increased complexity in data verification and validation.
Additionally, in the proton beam therapy system there are numerous safety features which typically require constant monitoring of the underlying hardware devices and subsystems to operate. A conventional approach to this monitoring requirement is to have hardware monitoring take place exclusively at a host application level by a controlling program or application. One potential drawback using this approach is that a failure of the host application or the controlling program may result in a potentially unsafe or hardware-damaging condition. In some instances a “watchdog” program is employed to detect lapses in communication between the host application and the monitored hardware however the use of a watchdog program may have undesirable effects on the system.
In the case of a power supply, the watchdog program may automatically shut off the power supply to thereby invoke a system safe. This may result in the cooling of the power supply and subsequently result in a lengthy warm up period before patient treatment can resume. Furthermore, a failure in the proton beam therapy system may be masked until just prior to treatment, possibly delaying the treatment and adding to the discomfort of the patient.
Hence, there is a need for an improved system and methods for managing communications within complex and loosely coupled distributed environments such as that used in a proton beam therapy device. This system architecture should be able to accommodate the complexity and bandwidth demands of the proton beam therapy system while maintaining an acceptable level of simplicity so as to facilitate scaling, maintenance, and development. Additionally, the system should provide improved system monitoring features that resolve potential problems associated with monitoring off-line or malfunctioning devices.